Results of behavioral and audiological tests with humans imply that ability to understand speech and other complex signals (particularly in a noisy listening situation) suffers loss from noise insult in excess of what could be inferred from pure tone thresholds measured in the quiet. These findings suggest that a complex interaction between the various levels of the auditory nervous system and functionally different receptors of the auditory end organ play a vital role in "sharpening" the sensory process. The objectives and techniques employed are very similar to Project 50003-03 and the projects are being merged. The objective is to use the rapid signal analysis ability of minicomputers to determine the auditory response to speech and speech-like signals including pseudo-random noise under normal conditions and conditions of auditory fatigue. Auditory fatigue and recovery process of single nerve fiber to speech and speech-like stimuli will be studied. Due to delays in obtaining key computer hardware from the computer manufacturer, we were unable to complete programming and interfacing of the computer during the 1976-77 period. It is anticipated that the data collection process can begin in several months.